I can't see it.
Merc has no reason to step back as they at the pointy end of the wedge and the old adage "Win on Sunday, Sell on Monday" still rings true. After all, they are a car company first and foremost.
I know what you mean! My pocketbook wishes Red Bull would win more, it's way cheaper buying a can of that over a new Mercedes every weekend! At least I don't have to worry about financing all those Ferraris anymore. (It's just as well Racing Point never wins, I've never seen a Racing Point for sale... well, once, but Stroll's dad bought it before they won, but it had a different name.)
But in all seriousness, I'm sure Mercedes is keeping a close eye on how effective the race team is at driving sales. What I liked about the Honda programme was they used it as an internal reward for Honda employees to get two years on the race team for a job well done. It hampered the race programme by using 'regular' people instead of career race engineers, but it was something to sell to the board.